1. App store- There's a reason that Apple features the App store so heavily in it's iPhone ads. Despite all the other great features, the single greatest thing the iPhone has going for it in terms of popularity is the App store. The commercials' tagline "There's an App for just about everything" is an understatement. From the most obscure productivity Apps to every conceivable board, card, arcade, and other game you can think of, there is literally an App for almost anything you can imagine. The awesome thing is that so many of them are free, in fact some of the best ones are.
2. The iPhone does everything well- Some phones are reasonably good at playing music. Others have good email functions (Blackberry). The iPhone has good to excellent just about everything. All iPhones come with built-in iPod functionality. Apple has refined the iPod function to a science, there is a reason that Apple products are the most popular MP3 player's out there. In addition to a great music experience, the iPhone is exceptional at surfing the internet thanks to it's large touch screen and multi-touch technology. If you try surfing the web on an iPhone after doing it on a Blackberry or flip phone, you will NEVER go back. I won't even get into the slick texting interface, easy of looking at multiple photo albums, etc.
3. Easy to use- Not unlike many other Apple products, the iPhone is extremely easy to use. Want to see the next page of Apps? Swipe your finger. Want to type in landscape (wide) mode? Turn the device 90 degrees. Some people have fears about a touchscreen only keyboard. Let me reassure you that it is very easy to use, especially in landscape mode. The autospeller is very good at detecting what word you meant to type, even if you mistype every letter.
4. Peace of mind- With fast 3G internet connection nearly everywhere you go and GPS capabilities coupled with Google maps, you will never be lost. Nor will you ever not be able to check some important email while on the road. Whether you are traveling, in a new area, or just doing your everyday routine, it's comforting to have such a powerful device handy. Should your car break down in the middle of nowhere, you can look up a tow truck and give them your exact location, thanks to Google maps with GPS.
5. Easy to switch-The switchover process is relatively painless once you decide to switch to an iPhone. AT&T will handle porting over your existing number so no concerns about needing a new number. Pick your plan, select your phone (now starting at $99) and you're good to go the second you walk out of the store. Worried about losing your existing phone contacts? No problem, they will transfer phone numbers from your old phone directly to your new iPhone.
Is it the cheapest smartphone/plan available? No. However, the surging widespread popularity of the iPhone in spite of the not so tiny pricetag should tell you something. Do you know anyone who switched from an iPhone to something else? Didn't think so. If you haven't done so yet, do yourself a favor and consider switching to an iPhone.